Add constraint verification update only on necessary actions

[Josipmrden]

Constraints are always verified in memgraph, even if edges are being added into the database only as a modification. Therefore, appropriate flag is being set in the transaction if constraints really need to be modified.

[master < Task] PR

• Check, and update documentation if necessary
• Provide the full content or a guide for the final git message

To keep docs changelog up to date, one more thing to do:

• Write a release note here, including added/changed clauses
• Tag someone from docs team in the comments

@vpavicic : Optimized verification of unique and existence constraints. Constraints are now not verified on nodes if exactly the properties that are triggering change in unique constraint indexes are updated.

[andrejtonev]

Looks good. Some comments (in part just from me being confused :))

[andrejtonev]

Looks good!